Celestron Advanced VX + Alignmaster

[williamnohair]

Hi everyone

anyone had experience of polar alignment using Alignmaster and the Celestron advanced vx mount? or indeed the accuracy of the built in polar alignment feature within the handset?

Despite using the Celestron polar scope and the polar alignment feature am still getting star trails. My setup is a permanent pier checked for levelness aligned with the scope from Celestron. The scope itself is good value for money but alas is not illuminated which makes life difficult as is the location of the altitude knob which could poke your eye out! The polar alignment feature 'syncs' on a star and appears to work but I still star trails!

Cheers

Bill 

[james_screech]

I've used the internal polar alignment routine. With one iteration I can get within 10' (according to the hand set).

Even with very good polar alignment long exposures will need guiding due to periodic error in the gears. The best unguided I can get with my AVX is about 10sec. when imaging with a ASi120MM & 8" SCT @ f5.4.

James

[williamnohair]

Thanks James

I am still learning guiding and am used to unguided Astrotrac + 200mm F2.8  images of up to a minute. Its practice time I am short on at the moment.

I just wish that these poxy clouds would clear!

Bill

[PeterCPC]

I use ASPA when imaging with my ED120 or ED80 and can get 4 minutes unguided. I have guided for 10 minutes with no star trails. 

Peter

[williamnohair]

Hi Peter

thanks for the info I am wondering if I am doing this right or not.

1 Polar align as best as possible

2 Two star alignment

3 Align to one calibration star

4 Chose another star and chose 'polar alignment' handset warns you if star is not right

5 Chose 'align mount' etc and follow instructions

The only improvement I can come up with is to use a webcam in the main OTA and some software to image with a cross hair on the screen to make sure I am cantered correctly which I have yet to try.

Anyway thanks for letting me know the mounts ability, I shall aim for a minute or so!

Cheers

Bill

[james_screech]

Hi Peter

thanks for the info I am wondering if I am doing this right or not.

1 Polar align as best as possible

2 Two star alignment

3 Align to one calibration star

4 Chose another star and chose 'polar alignment' handset warns you if star is not right

5 Chose 'align mount' etc and follow instructions

The only improvement I can come up with is to use a webcam in the main OTA and some software to image with a cross hair on the screen to make sure I am cantered correctly which I have yet to try.

Anyway thanks for letting me know the mounts ability, I shall aim for a minute or so!

Cheers

Bill

You would do better if you used more calibration stars. Also ensure that the when aligning on a star you always make the last hand controller moves in the same direction (RA should always be more right).

James

[PeterCPC]

Yes, I always do 2 calibration stars - seems to be enough. When you have done the first PA you should then do another alignment followed by another PA. After 2 iterations you should get a good PA. 

When you ask to "display align" after a PA, don't believe what it says - you need another alignment before "display align" works.

Peter

[james_screech]

When you ask to "display align" after a PA, don't believe what it says - you need another alignment before "display align" works.

Peter

I always park & power off after the first PA and then do another 2 star + 2/3 align.

James

[williamnohair]

Hi guys

thanks for all the advice, I have (and will again) try two calibration stars and then another polar align; what I would really like to ask all of you is (and this might sound really silly) do you use the finderscope to align or the OTA?

The bog standard finderscope is not that good and if you use the main scope you are guessing where the centre is (unless you have some form of cross hair setup). The reason I ask is that my eyesight is not that good and I struggle a bit. Also the finderscope only needs a nudge even after tightening and its out a bit from centre.

I want to be as accurate as possible.

Another quick question, on a permanent setup when powering up again you are prompted for date and time etc (which I thought the handset would store but doesn't) if you chose 'last alignment' should your scope be ok or do you have to do a two star setup every time you observe?

Thanks for all the advice on this, learning time is very limited here every minute counts

Bill

[PeterCPC]

I use an illuminated reticule 12mm eyepiece to align. I have also fitted a 9x50 finderscope with illuminated reticule. I don't power off but use the system described in the manual to unsync.

I also use the GPS module to save on all the inputs.

Peter

[james_screech]

You need to use the OTA for alignment the finder is not accurate enough.

The handset will store the date/time if you enable the RTC (see the manual for its location in the menu structure). If it does not then the battery may need replacing, its located on the mount inside the black plastic cover that contains the hand controller, guiding etc sockets. You should be able to find details online on replacing it. Though you do need to check the time as it does drift a bit.

I use my imaging camera with a reticule on the display for getting an accurate alignment. I usually get within 10' of the pole with one iteration.

James

[williamnohair]

Wow so  many tips!!!!!!

thanks all of you for your help and will try and sort out the time / date thing straight away as it really annoys me

Thanks again to all of you

Regards

Bill

[damnut]

Hi Bill,

Can tell why you have no hair, we are owned by two setters

[CSM]

You definitely need a 12mm reticule eyepiece or something similar.  Judging a star to be central you are likely to be way out.  Indeed, better still use a 2xBarlow and a 12mm reticule.

[Thalestris24]

Hi Bill

Are you guiding? You'll certainly need to with long focal lengths. With my AVX I ignore the hand controller alignment functions. Instead I drift align using PHD2 and I use Astrotortilla to sync and centre targets. If you have APT, the latest version integrates with Platesolve 2 though I've not tried it. I assume you've balanced your scope? I find the AVX rather difficult to balance because of its stiction.

Louise